This invention relates to power supplies, and more particularly to power supplies which may be used in a distributed power system. In a distributed power system, there is a main power supply, usually at a higher voltage, and the voltage from the main power supply is distributed throughout the system. At various locations throughout the system, smaller local distributed power supplies convert the distributed voltage to the voltage required locally, usually a much lower voltage. In present day distributed power systems local voltages of less than one volt to a few volts are common.
Usually, the distributed local power supplies are designed and rated for a wide range of input voltage, as an example, not a limitation, 48 volts nominal with a range of 32 to 75 volts. In many instances, this ability to accommodate a range of input voltages is not necessary, because the distributed voltage is (or could be) provided by a closely regulated voltage supply, as an example, not a limitation, 48 volts plus/minus one percent (1%). Many closely regulated power supplies have a remote sense capability, whereby the voltage drop in the conductors to a load may be compensated for.
The ability of the distributed local power supplies to accommodate a range of input voltages is very useful in some circumstances, but where it is not needed, it is wasteful, costly, bulky and adversely effects system performance and reliability. They are much less efficient than necessary and require a number of local controls and protection circuits because of their ability to regulate voltage autonomously. They are difficult to parallel.
Although envisioned for distributed power systems having a plurality of distributed local power supplies, this invention also relates to more simple power supplies wherein a first power supply provides a higher voltage and has a remote sense input, and a second power supply converts the output of the first power supply to a different output voltage.